The distribution of this species is very likely restricted only to Mexico, where populations are found in the Sierra Madre Oriental, in the Sierra Madre Occidental as well as in the Sierra Madre del Sur. Specimens of P. lilacina found East of the Isthmus of Mexico are doubtful and are probably the closely related species P. sharpii. Plants do occur mainly on slopes growing in mosses or directly in a loamy sandy soil in oak and pine forests. The species seems to be capable to adapt to a wider range of climatic conditions, as populations can be found in warmer, more drier subtropical climate as well as in more cooler and more moist mountain  cloud forests. Until now populations of P. lilacina were found in altitudes between 700 and 2400 m above sea level.

According to publications the flowering period of P. lilacina seems to vary. From own habitat observations s that flowering is occuring as long as the conditions are favourable and plants will die due to dry conditions or frost. In some habitats plants may flower all year round. Plants can produce up to 9 flower stalks. The light green coloured flower stalks can get 5 to 15 cm long and are densely covered with gland bearing hair.

The size of the flower is relatively small. The corolla consists of 5 corolla lobes. The lobes are 4 to 6 mm long and 2 to 4mm broad. The lobes of the upper lip are slightly smaller compared to the lower lobes. The form of the lobes can vary from rounded to elongated-obovate. The colours of the corolla lobes that can occur are violet, pale violet, pale purple and almost white. A typical character of this species is the white hump-like palate on the middle lobe of the lower lip. In addition the palate is covered with small white hair. The cylindircal corolla tube gets 3 to 5 mm long. In the inside of the tube there are 3 rows of white hair starting at the end of the palate. The outside of the tube shows a yellowish colour, turning more into white towards the spur. In addition the tube is covered with brown-violet veins. The green to yellow-brown coloured spur gets 2 to 4 mm long and forms an obtuse angle with the corolla tube.